Abstract

A method for forming a MEMS structure for an inertial sensor from fused silica includes: depositing a conductive layer on one or more selected regions of a first surface of a fused silica substrate, and illuminating areas of the fused silica substrate with laser radiation in a pattern defining features of the MEMS structure for an inertial sensor. A masking layer is deposited at least on the one or more selected regions of the first surface of the fused silica substrate where the conductive layer has been deposited, such that the illuminated areas of the fused silica substrate remain exposed. A first etch of the exposed areas of the fused silica substrate is performed so as to selectively etch the pattern defining features of the MEMS structure for an inertial sensor.

IPC Classes  ?

• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
• B81C 1/00 - Manufacture or treatment of devices or systems in or on a substrate
• G01C 19/5769 - Manufacturing; Mounting; Housings
• G01C 19/5755 - Structural details or topology the devices having a single sensing mass

Abstract

A signal processing system for a sensor. The system comprises a digital signal processing system configured to set a drive signal frequency for the primary drive transducer, a voltage controlled oscillator configured to receive an input indicative of the resonant frequency and to generate a first periodic signal at a first multiple of the resonant frequency, and a first phase locked loop, configured to receive the first periodic signal, and to generate a second periodic signal at a second multiple of the resonant frequency. The first and second periodic signals are used to control the operation of an analog-to-digital converter (ADC) configured to sample the primary pick off signal and a digital-to-analog converter (DAC) configured to generate a drive signal waveform applied to the primary drive transducer.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• H03L 7/099 - Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop - Details of the phase-locked loop concerning mainly the controlled oscillator of the loop

Abstract

A sensor package comprising: a sensor, wherein the sensor comprises a sensing structure formed in a material layer and one or more further material layers arranged to seal the sensing structure to form a hermetically sealed sensor unit; a support structure; one or more springs flexibly fixing the hermetically sealed sensor unit to the support structure; wherein the one or more springs are formed in the same material layer as the sensing structure of the sensor unit; and one or more external package wall(s) encapsulating the sensor unit, the support structure, and the one or more springs, wherein the support structure is fixed to at least one of the package wall(s). The springs decouple mechanical stresses between the sensor unit and the external package wall(s) so as to reduce the long term drift of scale factor and bias.

IPC Classes  ?

• G01P 1/02 - Housings
• G01P 1/00 - MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION OR SHOCK; INDICATING PRESENCE OR ABSENCE OF MOVEMENT;  INDICATING DIRECTION OF MOVEMENT  - Details of instruments

Abstract

A ground vehicle navigation system includes an inertial navigation system arranged to output an orientation estimate of the ground vehicle and a first position estimate of the ground vehicle, a terrain map comprising terrain data, a terrain gradient based navigation unit arranged to output a second position estimate of the ground vehicle based on a comparison between the orientation estimate and terrain gradient data extracted from the terrain map and an iterative algorithm unit arranged to determine a system error state in each iteration. In each iteration the iterative algorithm unit is arranged to receive the first position estimate and the second position estimate; and update the system error state for the next iteration based on the system error state, the first position estimate and the second position estimate. The iterative algorithm unit may then apply the updated system error state to the INS measurements.

IPC Classes  ?

• G01S 19/49 - Determining position by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system whereby the further system is an inertial position system, e.g. loosely-coupled
• G01S 13/931 - Radar or analogous systems, specially adapted for specific applications for anti-collision purposes of land vehicles
• G01C 21/34 - Route searching; Route guidance

Abstract

A terrain referenced navigation system includes a one sensor arranged to measure the elevation of terrain below a current position of the navigation system, a terrain elevation map comprising a plurality of map posts that each comprise terrain elevation data, and a land-water detection unit arranged to calculate a proportion of land and/or water of at least a portion of the terrain elevation map based on the terrain elevation data of said portion of said terrain elevation map. The land-water detection unit provides the ability to estimate a proportion of land and/or water of the terrain elevation map, using the terrain elevation data stored therein. The land-water detection unit allows the navigation system to detect areas of the map that contain transitions between land and water, and compensate accordingly when passing over these areas.

IPC Classes  ?

• G01S 13/931 - Radar or analogous systems, specially adapted for specific applications for anti-collision purposes of land vehicles
• G01S 19/47 - Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• G01S 19/51 - Relative positioning

Abstract

P) is measured after a predetermined time period to determine an oscillation cycle count during said predetermined time period.

IPC Classes  ?

• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• G01C 19/5712 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis the devices involving a micromechanical structure

Abstract

A vibrating structure angular rate sensor includes a mount, a planar vibrating structure and a plurality of compliant supports extending between the mount and the planar vibrating structure to support the vibrating structure thereby allowing the planar vibrating structure to oscillate in its plane relative to the mount in response to an electrical excitation. A first set of transducers is arranged on the planar vibrating structure to apply, in use, an electrical excitation to the planar vibrating structure and to sense, in use, motion resulting from oscillation of the planar vibrating structure in its plane. A plurality of capacitive regions is fixed at a distance from the planar vibrating structure in its plane. The capacitive regions form a second set of transducers configured to apply, in use, an electrostatic force to the planar vibrating structure which induces a change in the frequency of oscillation of the planar vibrating structure.

IPC Classes  ?

• H01L 41/113 - Piezo-electric or electrostrictive elements with mechanical input and electrical output
• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
• H01L 41/047 - Electrodes

Goods & Services

Inertial measurement units comprising accelerometers, gyroscopes, and gyrometers, and structural parts and fittings thereof; inertial measurement units comprising accelerometers, gyroscopes, and gyrometers for use in navigation and guidance systems and in tracking systems, and structural parts and fittings thereof

Abstract

B, of the DC voltage applied to the proof mass by the DC biasing element so as to provide a net electrostatic restoring force on the proof mass for balancing the inertial force of the applied acceleration and maintaining the proof mass at a null position, when the applied acceleration is greater than a threshold acceleration value.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01D 3/06 - Measuring arrangements with provision for the special purposes referred to in the subgroups of this group with provision for operation by a null method
• G01L 1/14 - Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass

Abstract

A terrain-referenced navigation system for an aircraft comprises: a stored digital terrain map; a position calculation unit arranged to calculate aircraft position relative to the stored digital terrain map to determine a terrain-referenced aircraft position; a fall line calculation unit arranged to calculate a fall line for a projectile starting from the terrain-referenced aircraft position as a launch point; and an impact point calculation unit arranged to directly compare the fall line with the digital terrain map, by incrementally comparing a height of the projectile along the fall line with a height of the terrain according to the stored digital terrain map in order to find an expected impact point on the terrain.

IPC Classes  ?

• F41G 9/00 - Systems for controlling missiles or projectiles, not provided for elsewhere

Abstract

A vibrating structure angular rate sensor comprises a MEMS structure includes a mount, a plurality of supporting structures fixed to the mount, and a vibrating planar ring structure flexibly supported by the plurality of supporting structures to move elastically relative to the mount. At least one primary drive transducer is arranged to cause the ring structure to oscillate in a primary mode at the resonant frequency of the primary mode. At least one primary pick-off transducer arranged to detect oscillation of the ring structure in the primary mode. At least three secondary pick-off transducers are arranged to detect oscillation of the ring structure in a secondary mode induced by Coriolis force when an angular rate is applied around an axis substantially perpendicular to the ring structure. At least one secondary drive transducer is arranged to null the induced oscillation in the secondary mode.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01C 19/5719 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis

Abstract

A method of demodulating a MEMS sensor pickoff signal from a vibrating resonator of said sensor, the method comprising: sampling the pickoff signal with an asynchronous ADC at a sampling rate of at least 50 times the resonant frequency of the resonator to generate a stream of samples; generating a first value by combining samples from said stream of samples according to a selected operation, said operation being selected in dependence on a synchronous clock signal that is synchronous to the resonant frequency of the resonator, said synchronous clock signal having a frequency at least twice the resonant frequency of the resonator; and counting the number of samples contributing to the first value. The increased sampling rate of the pickoff signal allows a much higher number of samples to be taken into account, thereby reducing noise. However, the ADC asynchronously from the resonator of the MEMS sensor.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• H03D 3/00 - Demodulation of angle-modulated oscillations

Abstract

A method of determining a reference direction for an angular measurement device, comprising: providing a rigid structure having an antenna for a global navigation satellite system (GNSS) fixed at a first point thereof; fixing the angular measurement device to a second point on the rigid structure, separated from the first point by at least 0.5 meters; while rotating the rigid structure so as to cause rotational movement of the antenna around the sensitive axis, acquiring velocity measurement data from the GNSS and angular velocity measurement data from the angular measurement device; and using the velocity measurement data and the angular velocity measurement data to determine a reference direction for the angular measurement device.

IPC Classes  ?

• G01S 19/47 - Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial

Abstract

A vibrating structure gyroscope includes a permanent magnet, a structure arranged in a magnetic field of the permanent magnet and arranged to vibrate under stimulation from at least one primary drive electrode and a drive system that includes: one primary drive electrode arranged at least one primary sense electrode arranged to sense motion in the vibrating structure and a drive control loop controlling the primary drive electrode dependent on the primary sense electrode. The structure also includes a compensation unit arranged to receive a signal from the drive system representative of a gain in the drive control loop and arranged to output a scale factor correction based on that signal. As the magnet degrades (e.g. naturally over time as the material ages), the magnetic field weakens. To compensate for this, the primary drive control loop will automatically increase the gain.

IPC Classes  ?

• G01C 19/5726 - Signal processing
• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
• G01C 19/5755 - Structural details or topology the devices having a single sensing mass
• G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A terrain-based navigation system include at least three laser range finders, each fixedly mounted to a vehicle body, each pointing in a different direction and arranged such that they can be used to calculate terrain gradient in two dimensions. Existing terrain-based navigation systems for aircraft that use a radar altimeter to determine the distance of the vehicle from the ground make use of the large field of view of the radar altimeter. The first return signal from the radar altimeter may not be from directly below the aircraft, but will be interpreted as being directly below the aircraft, thereby impairing the chances of obtaining a terrain match, or impairing the accuracy of a terrain match. The use of a plurality of laser range finders each fixedly mounted to the vehicle body allows more terrain information to be obtained as the terrain can be detected from the plurality of different directions.

IPC Classes  ?

• G01C 21/20 - Instruments for performing navigational calculations
• G01C 3/08 - Use of electric radiation detectors
• G01S 17/933 - Lidar systems, specially adapted for specific applications for anti-collision purposes of aircraft or spacecraft

Abstract

An inertial navigation system includes a first inertial measurement unit with at least a first sensor and a second inertial measurement unit with at least a second sensor corresponding in type to the first sensor. The first inertial measurement unit is rotatably mounted relative to the second inertial measurement unit, The inertial navigation system further include a controller arranged to: acquire a first set of measurements simultaneously from both the first inertial measurement unit and the second inertial measurement unit; rotate the first inertial measurement unit relative to the second inertial measurement unit; acquire a second set of measurements simultaneously from both the first inertial measurement unit and the second inertial measurement unit; and calculate from the first set of measurements and the second set of measurements at least one error characteristic of the first sensor and/or the second sensor.

IPC Classes  ?

• G01C 21/18 - Stabilised platforms, e.g. by gyroscope
• B64G 1/28 - Guiding or controlling apparatus, e.g. for attitude control using inertia or gyro effect
• G01C 19/5719 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass

Abstract

A sensor package includes a sensor, at least one external wall, and an interposer, arranged between the sensor and the at least one external wall. The sensor is wire bonded to the interposer and the interposer is wire bonded to the at least one external wall. Using an interposer, wire bonded to both the sensor and the at least one external wall, is an improved approach to electrically connecting a sensor and a sensor package. The interposer allows for short wire bonds from the sensor and the at least one external wall to the interposer, replacing the single, long wire bond from the sensor to the at least one external wall in the prior art. This provides improved resilience of the sensor package under high stress. Furthermore, it allows an existing sensor and package combination to be improved without needing to redesign either component.

IPC Classes  ?

• B81B 7/00 - Microstructural systems
• B81C 1/00 - Manufacture or treatment of devices or systems in or on a substrate

Abstract

A sensor package comprising: a sensor, wherein the sensor comprises a sensing structure formed in a material layer and one or more further material layers arranged to seal the sensing structure to form a hermetically sealed sensor unit; a support structure; one or more springs flexibly fixing the hermetically sealed sensor unit to the support structure; wherein the one or more springs are formed in the same material layer as the sensing structure of the sensor unit; and one or more external package wall(s) encapsulating the sensor unit, the support structure, and the one or more springs, wherein the support structure is fixed to at least one of the package wall(s). The springs decouple mechanical stresses between the sensor unit and the external package wall(s) so as to reduce the long term drift of scale factor and bias.

IPC Classes  ?

• G01P 1/02 - Housings
• G01P 1/00 - MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION OR SHOCK; INDICATING PRESENCE OR ABSENCE OF MOVEMENT;  INDICATING DIRECTION OF MOVEMENT  - Details of instruments

Abstract

2.

IPC Classes  ?

• G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A method of manufacturing an inertial measurement unit (IMU) comprises fabricating a plurality of individual MEMS inertial sensor packages at a package level as sealed packages containing a MEMS inertial sensor chip and an integrated circuit electrically connected together. Fabricating the individual MEMS inertial sensor packages comprises forming mechanical interconnect features in each package and assembling the IMU by mechanically interconnecting each individual MEMS inertial sensor package with another individual MEMS inertial sensor package in a mutually orthogonal orientation.

IPC Classes  ?

• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• G01P 1/02 - Housings
• B81B 7/00 - Microstructural systems
• G01C 19/5783 - Mountings or housings not specific to any of the devices covered by groups
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation

Abstract

1. The plurality of supporting structures comprises at least one active supporting structure which carries an active electrical connection from the annular member to the drive system; and at least one passive supporting structure which does not carry an active electrical connection from the annular member to the drive system.

IPC Classes  ?

• G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
• H03H 9/02 - Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators - Details
• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01C 19/5783 - Mountings or housings not specific to any of the devices covered by groups

Abstract

S. The gyroscope also includes digitally-controlled first and second sets to creating a static electrostatic balancing.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A sensing structure for an accelerometer includes a support and a proof mass mounted thereto by flexible legs. The proof mass has moveable electrode fingers perpendicular to the sensing direction and at least four fixed capacitor electrodes, with fixed capacitor electrode fingers perpendicular to the sensing direction. The fixed capacitor electrode fingers interdigitate with the movable electrode fingers and the proof mass is mounted to the support by an anchor on a centre line of the proof mass. The proof mass has an outer frame surrounding the fixed capacitor electrodes and the flexible legs extend laterally inwardly from the proof mass to the anchor. The fixed capacitor electrodes comprise two inner electrodes, one on each side of the proof mass centre line, and two outer electrodes, one on each side of the proof mass centre line.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

An annular resonator for a vibrating structure angular rate sensor comprises a planar annular member that lies in the X-Y plane and one or more supporting structures arranged to flexibly support the annular member in the X-Y plane. The one or more supporting structures each comprise a radial portion, extending radially from the annular member and having a first thickness in the X-Y plane, and a circumferential portion, extending circumferentially from the radial portion and having a second thickness in the X-Y plane, wherein the first thickness is greater than the second thickness.

IPC Classes  ?

• G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01C 19/5783 - Mountings or housings not specific to any of the devices covered by groups

Abstract

An inertial measurement system comprising: a first, roll gyro with an axis oriented substantially parallel to the spin axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros; operate a Kalman filter that receives a plurality of measurement inputs including at least roll angle, pitch angle and yaw angle and that outputs at least a roll angle error; initialise the Kalman filter with a roll angle error uncertainty representative of a substantially unknown roll angle; generate at least one pseudo-measurement from stored expected flight data; provide said pseudo-measurement(s) to the corresponding measurement input of the Kalman filter; and apply the roll angle error from the Kalman filter as a correction to the roll angle.

IPC Classes  ?

• G01C 21/18 - Stabilised platforms, e.g. by gyroscope
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• F42B 15/01 - Arrangements thereon for guidance or control

Abstract

A method for determining an operational characteristic of a vibrating structure gyroscope having a movable mass includes: driving the mass to oscillate along a first, predefined path; rotating the vibrating structure gyroscope so as to oscillate the mass along a second path, wherein the second path is different to the first, predefined path; sensing the oscillation of the mass along the second path so as to generate a sensing signal; converting the sensing signal into an in-phase signal and an out-of-phase signal using a demodulator, wherein the in-phase signal is in phase with the oscillation of the mass along the first path, and the out-of-phase signal is out of phase with the in-phase signal.

IPC Classes  ?

• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• G01C 19/5726 - Signal processing
• G01C 19/5755 - Structural details or topology the devices having a single sensing mass

Abstract

A method of determining whether parametric performance of an inertial sensor has been degraded comprises: recording first data output from an inertial sensor; then recording second data output from the inertial sensor; comparing the first data output with the second data output; and determining whether the parametric performance of the inertial sensor has been degraded based on the comparison between the first and second data output.

IPC Classes  ?

• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01P 15/18 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration in two or more dimensions
• G01P 15/09 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by piezoelectric pick-up
• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/12 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by alteration of electrical resistance

Abstract

b) formed on a surface of the insulative support layer axially spaced from the surface of the planar ring. The first and second sets of conductive electrode tracks are interdigitated with a lateral spacing between them in a radial direction. Each moveable conductive electrode track has a radial offset from a median line between adjacent fixed conductive electrode tracks such that each moveable conductive electrode track has a different lateral spacing from two different adjacent fixed conductive electrode tracks in opposite radial directions.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A capacitive accelerometer comprises: a substantially planar proof mass mounted to a fixed substrate by flexible support legs so as to be linearly moveable in an in-plane sensing direction. The proof mass comprises first and second sets of moveable capacitive electrode fingers. First and second sets of fixed capacitive electrode fingers interdigitates with the first and second sets of moveable electrode fingers respectively. A set of moveable damping fingers extend from the proof mass substantially perpendicular to the sensing direction, laterally spaced in the sensing direction. A set of fixed damping fingers mounted to the fixed substrate interdigitates with the set of moveable damping fingers and comprises an electrical connection to the proof mass so that the interdigitated damping fingers are electrically common. The damping fingers are mounted in a gaseous medium that provides a damping effect.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A navigation system comprising: an inertial navigation system arranged to output a first position estimate; a terrain based navigation unit arranged to output a second position estimate; a stored gravity map arranged to receive a position and to output gravity information for that position; and an iterative algorithm unit arranged to determine an INS error state in each iteration; wherein in each iteration the iterative algorithm unit is arranged to: receive the first position estimate and the second position estimate; determine a gravity corrected position estimate based on the first position estimate, the INS error state and the gravity information; and update the INS error state for the next iteration based on the INS error state, the gravity corrected position estimate and the second position estimate.

IPC Classes  ?

• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• G01C 23/00 - Combined instruments indicating more than one navigational value, e.g. for aircraft; Combined measuring devices for measuring two or more variables of movement, e.g. distance, speed or acceleration
• G01C 21/00 - Navigation; Navigational instruments not provided for in groups
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation

Abstract

A navigation system comprising: an inertial navigation system arranged to output a first position estimate; a terrain based navigation unit arranged to output a second position estimate; a gravity based navigation unit arranged to output a third position estimate; a stored gravity map arranged to receive a position and to output gravity information for that position; and an iterative algorithm unit arranged to determine an INS error state in each iteration; wherein in each iteration the iterative algorithm unit is arranged to: receive the first position estimate, the second position estimate, and the third position estimate; determine a gravity corrected position estimate based on the first position estimate, the INS error state and the gravity information; and update the INS error state for the next iteration based on the INS error state, the gravity corrected position estimate, the second position estimate and the third position estimate.

IPC Classes  ?

• G01C 21/00 - Navigation; Navigational instruments not provided for in groups
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 21/04 - Navigation; Navigational instruments not provided for in groups by terrestrial means

Abstract

An accelerometer closed loop control system comprising: a capacitive accelerometer comprising a proof mass moveable relative to first and second fixed capacitor electrodes; a PWM generator to generate in-phase and anti-phase PWM drive signals with an adjustable mark/space ratio, wherein said drive signals are applied to the first and second electrodes such that they are charged alternately; an output signal detector to detect a pick-off signal from the accelerometer representing a displacement of the proof mass from a null position to provide an error signal, wherein the null position is the position of the proof mass relative to the fixed electrodes when no acceleration is applied; a PWM servo operating in closed loop to vary the mark/space ratio of said PWM drive signals in response to the error signal so that mechanical inertial forces are balanced by electrostatic forces.

IPC Classes  ?

• G01P 15/11 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by magnetically sensitive devices by inductive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position

Abstract

An micro electro mechanical sensor comprising: a substrate; and a sensor element movably mounted to a first side of said substrate; wherein a second side of said substrate has a pattern formed in relief thereon. The pattern formed in relief on the second side of the substrate provides a reduced surface area for contact with the die bond layer. The reduced surface area reduces the amount of stress that is transmitted from the die bond layer to the substrate (and hence reduces the amount of transmitted stress reaching the MEMS sensor element). Because the substrate relief pattern provides a certain amount of stress decoupling, the die bond layer does not need to decouple the stress to the same extent as in previous designs. Therefore a thinner die bond layer can be used, which in turn allows the whole package to be slightly thinner.

IPC Classes  ?

• B81B 7/00 - Microstructural systems

Abstract

A mounting system for mounting an electronic component (2) in a housing (8) comprises a visco-elastic damping element (14, 20) for damping the transmission of vibration from the housing (8) to the component (2) in use, and a support (24, 52) for supporting the component (2) in the housing (8) independently of the damping element (14, 20) whereby the weight of the component (2) is substantially or completely removed from the damping element (14, 20). The support (24, 52) is configured to be selectively releasable from the component (2) such that the component (2) is then supported only by the damping element (14, 20).

IPC Classes  ?

• F42B 30/00 - Projectiles or missiles, not otherwise provided for, characterised by the ammunition class or type, e.g. by the launching apparatus or weapon used
• F42B 15/08 - Self-propelled projectiles or missiles, e.g. rockets; Guided missiles for carrying measuring instruments

Abstract

An assembly (2) for attachment to a projectile comprises a first part (4) and a second part (6) mounted for rotation relative to the first part (4) about an axis (A). There is an axial gap (G) between the first and second parts (4, 6). At least one plastically deformable element (34) is arranged within the gap (G) between the first and second parts (4, 6), the plastically deformable element (34) being such as to deform due to the closing of the axial gap (G) between the first and second parts (4, 6) during launch of the projectile.

IPC Classes  ?

• F42B 10/26 - Stabilising arrangements using spin
• F42C 19/02 - Fuze bodies; Fuze housings
• F42B 12/12 - Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect of armour-piercing type with shaped or hollow charge rotatably mounted with respect to missile housing
• F42B 12/00 - Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
• F42B 10/02 - Stabilising arrangements

Abstract

There is provided a method of sensing a rotation rate using a vibrating structure gyroscope, said gyroscope comprising an electronic control system comprising one or more control loops, wherein at least one of said control loops comprises a filter having a variable time constant, said method comprising the steps of: determining or estimating a characteristic of the vibrating structure of said gyroscope; and adapting or varying said time constant of said filter with the determined or estimated characteristic of said vibrating structure.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• G01D 1/16 - Measuring arrangements giving results other than momentary value of variable, of general application giving a value which is a function of two or more values, e.g. product or ratio

Abstract

A method of compensating for signal error is described, comprising: receiving a first signal from a first sensor, said first signal indicative of a movement characteristic; applying an error compensation to said first signal to produce an output signal; applying a variable gain factor to said error compensation; receiving a second signal from a second sensor indicative of said movement characteristic; wherein said error compensation is calculated using the difference between said output signal and said second signal, and said variable gain factor is calculated using said first signal.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• G01C 23/00 - Combined instruments indicating more than one navigational value, e.g. for aircraft; Combined measuring devices for measuring two or more variables of movement, e.g. distance, speed or acceleration

Abstract

An inertial measurement system for a spinning projectile comprising: first (roll), second and third gyros with axes arranged such that they define a three dimensional coordinate system; at least a first linear accelerometer; a controller, arranged to: compute a current projectile attitude comprising a roll angle, a pitch angle and a yaw angle; compute a current velocity vector from the accelerometer; combine a magnitude of said velocity vector with an expected direction for said vector to form a pseudo-velocity vector; provide the velocity vector and the pseudo-velocity vector to a Kalman filter that outputs a roll gyro scale factor error calculated as a function of the difference between the velocity vector and the pseudo-velocity vector; and apply the roll gyro scale factor error from the Kalman filter as a correction to the output of the roll gyro.

IPC Classes  ?

• G01C 21/18 - Stabilised platforms, e.g. by gyroscope
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01S 19/49 - Determining position by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

A successive approximation Analog to Digital Converter (ADC), comprising: a sample and hold device arranged to sample and hold an input signal at the beginning of a conversion cycle; a successive approximation register that sequentially builds up a digital output from its most significant bit to its least significant bit; a digital to analog converter that outputs a signal based on the output of the successive approximation register; a comparator that compares the output of the digital to analog converter with an output of the sample and hold device and supplies its output to the successive approximation register; and a residual signal storage device arranged to store the residual signal at the end of a conversion cycle; and wherein the successive approximation ADC is arranged to add the stored residual signal from the residual signal storage device to the input signal stored on the sample and hold device at the start of each conversion cycle. After each ADC full conversion by the SAR, the analog conversion of the digital output is as close to the original input signal as the resolution will allow. However there remains the residual part of the input signal that is smaller than what can be represented by the least significant bit of the digital output of the SAR. In normal operation, successive outputs of a SAR for the same input will result in the same digital value output and the same residual. By storing the residual at the end of each conversion and adding the residual onto the input signal of the next conversion the residuals are accumulated over time so that they may affect the output digital value. After a number of conversions, the accumulated residuals add up to more than the value represented by the LSB of the register and the digital value will be one higher than if a conversion had been performed on the input signal alone. In this way, the residual signal affects the output value in time and thus can be taken into account by processing the digital output in the time domain.

IPC Classes  ?

• H03M 1/06 - Continuously compensating for, or preventing, undesired influence of physical parameters
• H03M 1/08 - Continuously compensating for, or preventing, undesired influence of physical parameters of noise
• H03M 1/80 - Simultaneous conversion using weighted impedances
• H03M 1/46 - Analogue value compared with reference values sequentially only, e.g. successive approximation type with digital/analogue converter for supplying reference values to converter

Abstract

An inertial measurement system (200) for a longitudinal projectile, comprising a first, roll gyro to be oriented substantially parallel to the longitudinal axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro such that they define a three dimensional coordinate system. The system further comprises a controller (225, 250), arranged: —to compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; —for at least two time points, to compare the computed pitch and yaw angles with expected values for the pitch and yaw angles; —for each of said at least two time points, to calculate a roll angle error based on the difference between the computed pitch and yaw angles and the expected pitch and yaw angles; —to calculate a roll angle error difference between said at least two time points; —to calculate the total roll angle subtended between said at least two time points; —to calculate a roll angle scale factor error based on said computed roll angle error difference and said total subtended roll angle and apply the calculated roll angle scale factor error to the output of the roll gyro.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• F42B 15/01 - Arrangements thereon for guidance or control
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• F41G 7/36 - Direction control systems for self-propelled missiles based on predetermined target position data using inertial references
• F41G 7/00 - Direction control systems for self-propelled missiles

Abstract

A digitally controlled voltage controlled oscillator comprising an Nbit digital to analogue convertor arranged to receive a frequency change demand signal as a digital Nbit word, and having an output provided via an integrator to a voltage controlled oscillator configured to provide a frequency output.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• G01C 19/66 - Ring laser gyrometers
• H03L 7/099 - Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop - Details of the phase-locked loop concerning mainly the controlled oscillator of the loop

Abstract

An inertial sensor includes a substantially planar, rotationally symmetric proof mass, a capacitive pick-off circuit connected to the proof mass, an electrical drive circuit connected to the four pairs of electrodes. The drive circuit is arranged to apply first in-phase and anti-phase pulse width modulation (PWM) drive signals with a first frequency to the first and third electrode pairs, such that one electrode in each pair is provided with in-phase PWM drive signals and the other electrode in each pair is provided with anti-phase PWM drive signals and to apply second in-phase and anti-phase PWM drive signals with a second frequency, different to the first frequency, to the second and fourth electrode pairs, such that one electrode in each pair is provided with in-phase PWM drive signals and the other electrode in each pair is provided with anti-phase PWM drive signals.

IPC Classes  ?

• G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• G01P 15/18 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration in two or more dimensions
• G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
• G01C 19/5762 - Structural details or topology the devices having a single sensing mass the sensing mass being connected to a driving mass, e.g. driving frames
• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01P 15/097 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by vibratory elements
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

An inertial measurement system for a spinning projectile includes: a first, roll gyro to be oriented substantially parallel to the spin axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; calculate a roll angle error; provide the roll angle error as an input to a Kalman filter that outputs a roll angle correction and a roll rate scale factor correction; and apply the calculated roll angle correction and roll rate scale factor correction to the output of the roll gyro.

IPC Classes  ?

• F42B 15/01 - Arrangements thereon for guidance or control
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01P 13/02 - Indicating direction only, e.g. by weather vane
• G05D 1/10 - Simultaneous control of position or course in three dimensions
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• F41G 7/36 - Direction control systems for self-propelled missiles based on predetermined target position data using inertial references

Abstract

2′ to a second set of fixed capacitive electrode fingers. This provides a net electrostatic restoring force on the proof mass for balancing the inertial force of the applied acceleration and maintains the proof mass at a null position.

IPC Classes  ?

• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

In a method for open loop operation of a capacitive accelerometer, a first mode of operation comprises electrically measuring a deflection of a proof mass (204) from the null position under an applied acceleration using a pickoff amplifier (206) set to a reference voltage Vcm. A second mode of operation comprises applying electrostatic forces in order to cause the proof mass (204) to deflect from the null position, and electrically measuring the forced deflection so caused. In the second mode of operation the pickoff amplifier (206) has its input (211) switched from Vcm to Vss, using a reference control circuit (209), so that drive amplifiers (210) can apply different voltages Vdd to the proof mass (204) and associated fixed electrodes (202).

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A sensor comprises a substrate 16 and a sensor element 20 anchored to the substrate 16, the substrate 16 and sensor element 20 being of dissimilar materials and having different coefficients of thermal expansion, the sensor element 20 and substrate 16 each having a generally planar face arranged substantially parallel to one another, the sensor further comprising a spacer 26, the spacer 26 being located so as to space at least part of the sensor element 20 from at least part of the substrate 16, wherein the spacer 26 is of considerably smaller area than the area of the smaller of face of the substrate 16 and that of the sensor element 20.

IPC Classes  ?

• G01C 19/5783 - Mountings or housings not specific to any of the devices covered by groups
• B81B 7/00 - Microstructural systems
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes

Abstract

A method for closed loop operation of a capacitive accelerometer comprising: a proof mass; first and second sets of both fixed and moveable capacitive electrode fingers, interdigitated with each other; the method comprising: applying PWM drive signals to the fixed fingers; sensing displacement of the proof mass and changing the mark:space ratio of the PWM drive signals, to provide a restoring force on the proof mass that balances the inertial force of the applied acceleration and maintains the proof mass at a null position; detecting when the mark:space ratio for the null position is beyond a predetermined upper or lower threshold; and further modulating the PWM drive signals by extending or reducing x pulses in every y cycles, where x>1 and y>1, to provide an average mark:space ratio beyond the upper or lower threshold without further increasing or decreasing the mark length of the other pulses.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A method of determining whether parametric performance of an inertial sensor has been degraded comprises: recording first data output from an inertial sensor; then recording second data output from the inertial sensor; comparing the first data output with the second data output; and determining whether the parametric performance of the inertial sensor has been degraded based on the comparison between the first and second data output.

IPC Classes  ?

• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation

Abstract

A capacitive accelerometer (202) comprises: a substantially planar proof mass (204) mounted to a fixed substrate by flexible support legs (250) so as to be linearly moveable in an in-plane sensing direction (200). The proof mass comprises first and second sets of moveable capacitive electrode fingers. First and second sets of fixed capacitive electrode fingers interdigitates with the first and second sets of moveable electrode fingers respectively (221, 222). A set of moveable damping fingers (224) extend from the proof mass substantially perpendicular to the sensing direction, laterally spaced in the sensing direction. A set of fixed damping fingers (222) mounted to the fixed substrate interdigitates with the set of moveable damping fingers and comprises an electrical connection (260) to the proof mass so that the interdigitated damping fingers (228, 230) are electrically common. The damping fingers are mounted in a gaseous medium that provides a damping effect.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• B81B 5/00 - Devices comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements

Abstract

An angular velocity sensor comprises: an insulative support layer (10); a substrate layer (8) formed of a silica-based material and comprising a planar ring structure (2) mounted to vibrate in-plane; and a plurality of conductive electrodes (14), each comprising a first set of moveable conductive electrode tracks (14a) formed on a surface of the planar ring and a second set of fixed conductive electrode tracks (14b) formed on a surface of the insulative support layer axially spaced from the surface of the planar ring. The first and second sets of conductive electrode tracks are interdigitated with a lateral spacing between them in a radial direction. Each moveable conductive electrode track has a radial offset from a median line between adjacent fixed conductive electrode tracks such that each moveable conductive electrode track has a different lateral spacing from two different adjacent fixed conductive electrode tracks in opposite radial directions.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

An inertial measurement system for a longitudinal projectile comprising: a first, roll gyro to be oriented substantially parallel to the longitudinal axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro such that they define a three dimensional coordinate system; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; compare the computed pitch and yaw angles with expected values for the pitch and yaw angles; calculate a roll angle error and a roll scale factor error based on the difference between the computed pitch and yaw angles and the expected pitch and yaw angles; and apply the calculated roll angle error and roll scale factor error to the output of the roll gyro.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 19/02 - Rotary gyroscopes
• F41G 7/36 - Direction control systems for self-propelled missiles based on predetermined target position data using inertial references
• G05D 1/10 - Simultaneous control of position or course in three dimensions

Abstract

A sensing structure for an accelerometer includes a support and a proof mass mounted to the support by flexible legs for in-plane movement in response to an applied acceleration along a sensing direction. The proof mass includes a plurality of moveable electrode fingers extending substantially perpendicular to the sensing direction and spaced apart in the sensing direction. The structure also includes at least one pair of fixed capacitor electrodes comprising first and second sets of fixed electrode fingers extending substantially perpendicular to the sensing direction and spaced apart in the sensing direction; the first set of fixed electrode fingers arranged to interdigitate with the moveable electrode fingers with a first offset in one direction from a median line therebetween, and the second set of fixed electrode fingers arranged to interdigitate with the moveable electrode fingers with a second offset in the opposite direction from a median line therebetween.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A capacitive accelerometer including: at least one additional fixed capacitor electrode with a plurality of additional fixed capacitive electrode fingers extending along the sensing direction. The proof mass comprises a plurality of moveable capacitive electrode fingers extending from the proof mass along the sensing direction and arranged to interdigitate with the plurality of additional fixed capacitive electrode fingers of the at least one additional fixed capacitor electrode. A means is provided for applying a voltage to the at least one additional fixed capacitor electrode to apply an electrostatic force to the plurality of moveable capacitive electrode fingers that acts to pull the proof mass towards the at least one further fixed capacitor electrode and thereby reduces the lateral spacings between the movable capacitive electrode fingers of the proof mass and the first and second sets of fixed capacitive electrode fingers that provide electrostatic forces for sensing purposes.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• B81B 5/00 - Devices comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A mounting system for mounting an electronic component (2) in a housing (8) comprises a visco-elastic damping element (14, 20) for damping the transmission of vibration from the housing (8) to the component (2) in use, and a support (24, 52) for supporting the component (2) in the housing (8) independently of the damping element (14, 20) whereby the weight of the component (2) is substantially or completely removed from the damping element (14, 20). The support (24, 52) is configured to be selectively releasable from the component (2) such that the component (2) is then supported only by the damping element (14, 20).

IPC Classes  ?

• F42B 15/08 - Self-propelled projectiles or missiles, e.g. rockets; Guided missiles for carrying measuring instruments
• F42B 30/00 - Projectiles or missiles, not otherwise provided for, characterised by the ammunition class or type, e.g. by the launching apparatus or weapon used

Abstract

An assembly (2) for attachment to a projectile comprises a first part (4) and a second part (6) mounted for rotation relative to the first part (4) about an axis (A). There is an axial gap (G) between the first and second parts (4, 6). At least one plastically deformable element (34) is arranged within the gap (G) between the first and second parts (4, 6), the plastically deformable element (34) being such as to deform due to the closing of the axial gap (G) between the first and second parts (4, 6) during launch of the projectile.

IPC Classes  ?

• F42B 10/26 - Stabilising arrangements using spin
• F42C 19/02 - Fuze bodies; Fuze housings

Abstract

A closed loop method of controlling a capacitive accelerometer uses two servo loops. A Vcrit servo loop uses an output signal (S2) modulated by a sine wave signal (S1). The Vcrit control signal adjusts the magnitude of the PWM drive signals applied to the fixed capacitor electrodes of the accelerometer, thereby optimising open loop gain.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A method of compensating for signal error is described, comprising: receiving a first signal from a first sensor, said first signal indicative of a movement characteristic; applying an error compensation to said first signal to produce an output signal; applying a variable gain factor to said error compensation; receiving a second signal from a second sensor indicative of said movement characteristic; wherein said error compensation is calculated using the difference between said output signal and said second signal, and said variable gain factor is calculated using said first signal.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass

Abstract

There is provided a method of sensing a rotation rate using a vibrating structure gyroscope, said gyroscope comprising an electronic control system comprising one or more control loops, wherein at least one of said control loops comprises a filter having a variable time constant, said method comprising the steps of: determining or estimating a characteristic of the vibrating structure of said gyroscope; and adapting or varying said time constant of said filter with the determined or estimated characteristic of said vibrating structure.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups

Abstract

An aircraft ground collision detection system comprising: an object detection device for mounting on an aircraft and arranged to detect objects and output the location of each detected object; and a processor arranged to: receive the ground speed of the aircraft and the heading of the aircraft and the detected location of each detected object; predict the aircraft's path based on the ground speed and the heading; compare the predicted aircraft path with the object locations; and output an alert based on the overlap or proximity of the predicted aircraft path with the object locations. By predicting the path of the aircraft based on detected ground speed and heading, the system can accurately assess which detected objects pose a collision threat.

IPC Classes  ?

• G08G 5/04 - Anti-collision systems
• G08G 5/06 - Traffic control systems for aircraft for control when on the ground
• G01S 13/93 - Radar or analogous systems, specially adapted for specific applications for anti-collision purposes
• G08G 5/00 - Traffic control systems for aircraft

Abstract

A successive approximation Analogue to Digital Converter (ADC), comprising: a sample and hold device arranged to sample and hold an input signal at the beginning of a conversion cycle; a successive approximation register that sequentially builds up a digital output from its most significant bit to its least significant bit; a digital to analogue converter that outputs a signal based on the output of the successive approximation register; a comparator that compares the output of the digital to analogue converter with an output of the sample and hold device and supplies its output to the successive approximation register; and a residual signal storage device arranged to store the residual signal at the end of a conversion cycle; and wherein the successive approximation ADC is arranged to add the stored residual signal from the residual signal storage device to the input signal stored on the sample and hold device at the start of each conversion cycle. After each ADC full conversion by the SAR, the analogue conversion of the digital output is as close to the original input signal as the resolution will allow. However there remains the residual part of the input signal that is smaller than what can be represented by the least significant bit of the digital output of the SAR. In normal operation, successive outputs of a SAR for the same input will result in the same digital value output and the same residual. By storing the residual at the end of each conversion and adding the residual onto the input signal of the next conversion the residuals are accumulated over time so that they may affect the output digital value. After a number of conversions, the accumulated residuals add up to more than the value represented by the LSB of the register and the digital value will be one higher than if a conversion had been performed on the input signal alone. In this way, the residual signal affects the output value in time and thus can be taken into account by processing the digital output in the time domain.

IPC Classes  ?

• H03M 1/06 - Continuously compensating for, or preventing, undesired influence of physical parameters
• H03M 1/46 - Analogue value compared with reference values sequentially only, e.g. successive approximation type with digital/analogue converter for supplying reference values to converter

Abstract

An inertial measurement system (200) for a longitudinal projectile, comprising a first, roll gyro to be oriented substantially parallel to the longitudinal axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro such that they define a three dimensional coordinate system. The system further comprises a controller (225, 250), arranged: - to compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; - for at least two time points, to compare the computed pitch and yaw angles with expected values for the pitch and yaw angles; - for each of said at least two time points, to calculate a roll angle error based on the difference between the computed pitch and yaw angles and the expected pitch and yaw angles; - to calculate a roll angle error difference between said at least two time points; - to calculate the total roll angle subtended between said at least two time points; - to calculate a roll angle scale factor error based on said computed roll angle error difference and said total subtended roll angle and apply the calculated roll angle scale factor error to the output of the roll gyro.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• F41G 7/36 - Direction control systems for self-propelled missiles based on predetermined target position data using inertial references
• F42B 15/01 - Arrangements thereon for guidance or control
• G05D 1/10 - Simultaneous control of position or course in three dimensions

Abstract

A digitally controlled voltage controlled oscillator comprising an Nbit digital to analogue convertor arranged to receive a frequency change demand signal as a digital Nbit word, and having an output provided via an integrator to a voltage controlled oscillator configured to provide a frequency output.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• H03L 7/08 - Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop - Details of the phase-locked loop

Abstract

c and represents an in-phase digital reference signal substantially in the form of a sine and/or cosine wave; and multiplying the input bit stream with the in-phase reference bit stream to produce an output bit stream representing the amplitude modulation of the analog signal.

IPC Classes  ?

• H03K 3/017 - Adjustment of width or dutycycle of pulses
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• H03D 1/18 - Demodulation of amplitude-modulated oscillations by means of non-linear elements having more than two poles of semiconductor devices
• H03M 1/12 - Analogue/digital converters
• H03M 3/00 - Conversion of analogue values to or from differential modulation

Abstract

A method for closed loop operation of a capacitive accelerometer uses a single current source (62) and a single current sink (64) to apply an in-phase drive signal V1 ' to a first set of fixed capacitive electrode fingers and a corresponding anti-phase drive signal V 2 'to a second set of fixed capacitive electrode fingers. This provides a net electrostatic restoring force on the proof mass for balancing the inertial force of the applied acceleration and maintains the proof mass at a null position.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

In a method for open loop operation of a capacitive accelerometer, a first mode of operation comprises electrically measuring a deflection of a proof mass (204) from the null position under an applied acceleration using a pickoff amplifier (206) set to a reference voltage Vcm. A second mode of operation comprises applying electrostatic forces in order to cause the proof mass (204) to deflect from the null position, and electrically measuring the forced deflection so caused. In the second mode of operation the pickoff amplifier (206) has its input (211) switched from Vcm to Vss, using a reference control circuit (209), so that drive amplifiers (210) can apply different voltages Vdd to the proof mass (204) and associated fixed electrodes (202).

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A method for closed loop operation of a capacitive accelerometer comprising: a proof mass; first and second sets of both fixed and moveable capacitive electrode fingers, interdigitated with each other; the method comprising: applying PWM drive signals to the fixed fingers; sensing displacement of the proof mass and changing the mark:space ratio of the PWM drive signals, to provide a restoring force on the proof mass that balances the inertial force of the applied acceleration and maintains the proof mass at a null position; detecting when the mark:space ratio for the null position is beyond a predetermined upper or lower threshold; and further modulating the PWM drive signals by extending or reducing x pulses in every y cycles, where x>l and y>l, to provide an average mark:space ratio beyond the upper or lower threshold without further increasing or decreasing the mark length of the other pulses.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass

Abstract

An inertial measurement system for a longitudinal projectile comprising :a first, roll gyro to be oriented substantially parallel to the longitudinal axis of the projectile;a second gyro and a third gyro with axes arranged with respect to the roll gyro such that they define a three dimensional coordinate system; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; compare the computed pitch and yaw angles with expected values for the pitch and yaw angles;calculate a roll angle error and a roll scale factor error based on the difference between the computed pitch and yaw angles and the expected pitch and yaw angles; and apply the calculated roll angle error and roll scale factor error to the output of the roll gyro. Calculating both roll angle error and roll scale factor error as corrections in the inertial measurement system allows much better control and correction of the calculated roll angle from the roll gyroscope even at high roll rates (e.g. 10-20 rotations per second). This correction system compensates for the large errors that can arise in inexpensive gyroscopes and therefore allows an accurate navigational system to be built with inexpensive components. No additional attitude sensors such as magnetometers are required, again reducing the cost and complexity of the system.

IPC Classes  ?

• G01C 19/02 - Rotary gyroscopes
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G05D 1/10 - Simultaneous control of position or course in three dimensions

Abstract

A sensing structure for an accelerometer, comprising: a proof mass mounted to a support by flexible legs for in-plane movement in response to an applied acceleration along a sensing direction; the proof mass comprising a plurality of moveable electrode fingers extending substantially perpendicular to and spaced apart in the sensing direction; at least one pair of fixed capacitor electrodes comprising first and second sets of fixed electrode fingers extending substantially perpendicular to and spaced apart in the sensing direction; the first and second sets of fixed electrode fingers interdigitate with the moveable electrode fingers with a first and second offset in one direction and in the opposite direction, respectively, from a median line therebetween; wherein the proof mass is an outer frame surrounding the fixed capacitor electrodes, the flexible legs extending laterally inwardly from the proof mass to a central anchor.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Goods & Services

Inertial measurement units comprising accelerometers and gyros; inertial measurement units comprising accelerometers and gyros, for use in navigation and guidance systems and in tracking systems; structural parts and fittings for all the aforesaid goods.

Abstract

A capacitive accelerometer including: at least one additional fixed capacitor electrode with a plurality of additional fixed capacitive electrode fingers extending along the sensing direction. The proof mass comprises a plurality of moveable capacitive electrode fingers extending from the proof mass along the sensing direction and arranged to interdigitate with the plurality of additional fixed capacitive electrode fingers of the at least one additional fixed capacitor electrode. A means is provided for applying a voltage to the at least one additional fixed capacitor electrode to apply an electrostatic force to the plurality of moveable capacitive electrode fingers that acts to pull the proof mass towards the at least one further fixed capacitor electrode and thereby reduces the lateral spacings between the movable capacitive electrode fingers of the proof mass and the first and second sets of fixed capacitive electrode fingers that provide electrostatic forces for sensing purposes.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• B81B 5/00 - Devices comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position

Abstract

A closed loop method of controlling a capacitive accelerometer (1) uses two servo loops. A Vcrit servo loop (32) uses an output signal (S2) modulated by a sine wave signal (S1). The Vcrit control signal adjusts the magnitude of the PWM drive signals applied to the fixed capacitor electrodes of the accelerometer (1), thereby optimising open loop gain.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A vibratory ring structure is described which comprises a ring body and at least one ring electrode secured thereto, the or each ring electrode extending over a first angular extent and: being attached to the ring body over second angular extent, wherein the first angular extent is greater than the second angular extent.

IPC Classes  ?

• G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01P 15/14 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of gyroscopes

Abstract

A sensor comprises a substrate (16) and a sensor element (20) anchored to the substrate (16), the substrate (16) and sensor element (20) being of dissimilar materials and having different coefficients of thermal expansion, the sensor element (20) and substrate (16) each having a generally planar face arranged substantially parallel to one another, the sensor further comprising a spacer (26), the spacer (26) being located so as to space at least part of the sensor element (20) from at least part of the substrate (16), wherein the spacer (26) is of considerably smaller area than the area of the smaller of face of the substrate (16) and that of the sensor element (20).

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• B81B 7/00 - Microstructural systems
• G01C 19/5783 - Mountings or housings not specific to any of the devices covered by groups
• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes

Abstract

A method of reactive ion etching a substrate 46 to form at least a first and a second etched feature (42, 44) is disclosed. The first etched feature (42) has a greater aspect ratio (depth:width) than the second etched feature (44). In a first etching stage the substrate (46) is etched so as to etch only said first feature (42) to a predetermined depth. Thereafter in a second etching stage, the substrate (46) is etched so as to etch both said first and said second features (42, 44) to a respective depth. A mask (40) may be applied to define apertures corresponding in shape to the features (42, 44). The region of the substrate (46) in which the second etched feature (44) is to be produced is selectively masked with a second maskant (50) during the first etching stage, The second maskant (50) is then removed prior to the second etching stage.

IPC Classes  ?

• H01L 21/311 - Etching the insulating layers
• H01L 21/302 - Treatment of semiconductor bodies using processes or apparatus not provided for in groups to change the physical characteristics of their surfaces, or to change their shape, e.g. etching, polishing, cutting
• H01L 21/461 - Treatment of semiconductor bodies using processes or apparatus not provided for in groups to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
• H01L 29/06 - Semiconductor bodies characterised by the shapes, relative sizes, or dispositions of the semiconductor regions
• B81C 1/00 - Manufacture or treatment of devices or systems in or on a substrate
• B81B 3/00 - Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
• H01L 21/3065 - Plasma etching; Reactive-ion etching
• H01L 21/308 - Chemical or electrical treatment, e.g. electrolytic etching using masks

Abstract

A device is described herein for determining azimuth comprising a MEMS inertial measurement unit (IMU), a GPS system comprising a GPS antenna and receiver, and a processor configured to receive data from said IMU and from said GPS system, said processor being configured to process said IMU data and said GPS data to derive a true north reference based on said IMU data and said GPS data. A method for determining azimuth is also described herein.

IPC Classes  ?

• G01C 21/00 - Navigation; Navigational instruments not provided for in groups
• G01C 15/00 - Surveying instruments or accessories not provided for in groups
• G01C 17/00 - Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes
• G01C 21/10 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration
• G01S 19/39 - Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• G01S 19/53 - Determining attitude
• G01S 19/54 - Determining attitude using long or short baseline interferometry
• G01S 19/35 - Constructional details or hardware or software details of the signal processing chain
• G01C 19/38 - Rotary gyroscopes for indicating a direction in the horizontal plane, e.g. directional gyroscopes with north-seeking action by other than magnetic means, e.g. gyrocompasses using earth's rotation

Abstract

A vibratory gyroscope is provided comprising a plurality of secondary pickoff transducers which are each sensitive to the secondary response mode, wherein: at least two of the secondary pickoff transducers comprise skew transducers designed to be sensitive to the primary mode which produce an induced quadrature signal in response thereto. A method of using the gyroscope is provided comprising the steps of arranging electrical connections between the secondary pickoff transducers and a pickoff amplifier so that in use the induced quadrature signal is substantially rejected by the amplifier in the absence of a fault condition, and the amplifier outputs an induced quadrature signal when a fault condition disconnects one of the skew transducers from the amplifier, and a comparator compares the quadrature output from the pickoff amplifier with a predetermined threshold value and provides a fault indication when the predetermined threshold is exceeded.

IPC Classes  ?

• G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A MEMS sensor comprises a vibrating sensing structure formed from a semiconductor substrate layer (50). The semiconductor substrate layer (50) is mounted on a pedestal comprising an electrically insulating substrate layer (52) bonded to the semiconductor substrate (50) to form a rectangular sensor chip. The pedestal further comprises an electrically insulating spacer layer (54) for mounting the sensor chip to a housing. The electrically insulating spacer layer (54) is octagonal. When the vibrating sensing structure is excited into a cos 2θ vibration mode pair, the quadrature bias arising from any mode frequency split is not affected by changes in temperature as a result of the octagonal spacer layer (54).

IPC Classes  ?

• G01C 19/00 - Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
• G01P 3/44 - Devices characterised by the use of electric or magnetic means for measuring angular speed
• G01P 9/00 - Measuring speed by using gyroscopic effect, e.g. using gas or using electron beam (using turn-sensitive devices or angular rate sensors using vibrating masses G01C 19/56)
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• G01C 19/5719 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01C 19/5769 - Manufacturing; Mounting; Housings

Abstract

An electronic device comprises a circuit substrate (5), and a moulded interconnect device (4) incorporating integral legs (8) to mount the interconnect device upon the substrate, the legs spacing at least one of the legs carrying a conducting track (20, 21, 22) to provide an electrical interconnection between the interconnect device and the substrate. The substrate (5) may comprise another moulded interconnect device and may be mounted upon a processor (3) and may include an electromagnetic shield (30) on its lower surface.

IPC Classes  ?

• H01R 12/00 - Structural associations of a plurality of mutually-insulated electrical connecting elements, specially adapted for printed circuits, e.g. printed circuit boards [PCB], flat or ribbon cables, or like generally planar structures, e.g. terminal strips, ; Coupling devices specially adapted for printed circuits, flat or ribbon cables, or like generally planar structures; Terminals specially adapted for contact with, or insertion into, printed circuits, flat or ribbon cables, or like generally planar structures
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01S 19/35 - Constructional details or hardware or software details of the signal processing chain
• H05K 1/14 - Structural association of two or more printed circuits
• H05K 1/11 - Printed elements for providing electric connections to or between printed circuits
• G01S 19/13 - Receivers
• H05K 7/10 - Plug-in assemblages of components

Abstract

a).

IPC Classes  ?

• G01P 15/135 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by making use of contacts which are actuated by a movable inertial mass
• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Goods & Services

Inertial measurement unit comprised of multi-axis angular rate data and acceleration sensors.

Goods & Services

Inertial measurement unit comprised of multi-axis angular rate data and acceleration sensors.

Goods & Services

Inertial measurement unit (IMU) used in air navigation for measuring velocity, orientation and gravitational forces, comprised of multi-axis angular rate data and acceleration sensors

Abstract

An accelerometer comprises a support, a first mass element and a second mass element, the mass elements being rigidly interconnected to form a unitary movable proof mass, the support being located at least in part between the first and second mass elements, a plurality of mounting legs securing the mass elements to the support member, at least two groups of movable capacitor fingers provided on the first mass element and interdigitated with corresponding groups of fixed capacitor fingers associated with the support, and at least two groups of movable capacitor fingers provided on the second mass element and interdigitated with corresponding groups of fixed capacitor fingers associated with the support.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/18 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration in two or more dimensions
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A vibratory ring structure is described which comprises a ring body and at least one ring electrode secured thereto, the or each ring electrode extending over a first angular extent and: being attached to the ring body over second angular extent, wherein the first angular extent is greater than the second angular extent.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A method of tuning a vibratory ring structure is described which comprises determining an angular spacing for a pair of fine tuning holes (16) of substantially the same size, located on or near the neutral axis of the vibratory ring structure (10), the angular offset being selected to reduce to an acceptable level the frequency split between the target normal mode and a further normal mode which Is angularly offset relative to the target normal mode, and forming the pair of fine tuning holes (16) in the vibratory ring structure (10) at the determined angular spacing, A ring structure, for example a gyroscope, tuned or balanced in this manner is also disclosed.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A silicon MEMS gyroscope is described having a ring or hoop-shaped resonator. The resonator is formed by a Deep Reactive Ion Fitch technique and is formed with slots extending around the circumference of the resonator on either side of the neutral axis of the resonator. The slots improve the Quality Factor Q of the gyroscope without affecting the resonant frequency of the resonator.

IPC Classes  ?

• G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure
• G01C 19/5719 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis

Abstract

A sensor comprises a substrate (16) and a sensor element (20) anchored to the substrate (16), the substrate (16) and sensor element (20) being of dissimilar materials and having different coefficients of thermal expansion, the sensor element (20) and substrate (16) each having a generally planar face arranged substantially parallel to one another, the sensor further comprising a spacer (26), the spacer (26) being located so as to space at least part of the sensor element (20) from at least part of the substrate (16), wherein the spacer (26) is of considerably smaller area than the area of the smaller of face of the substrate (16) and that of the sensor element (20).

IPC Classes  ?

• B81B 7/00 - Microstructural systems
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

An electronic device comprises a circuit substrate, and a moulded interconnect device incorporating integral legs to mount the interconnect device upon the substrate, the legs spacing at least part of the interconnect device from the substrate, at least one of the legs carrying a conducting track to provide an electrical interconnection between the interconnect device and the substrate.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01S 19/35 - Constructional details or hardware or software details of the signal processing chain
• H05K 1/14 - Structural association of two or more printed circuits

Abstract

A vibratory gyroscope is provided comprising a plurality of secondary pickoff transducers which are each sensitive to the secondary response mode, wherein: at least two of the secondary pickoff transducers comprise skew transducers designed to be sensitive to the primary mode which produce an induced quadrature signal in response thereto. A method of using the gyroscope is provided comprising the steps of arranging electrical connections between the secondary pickoff transducers and a pickoff amplifier so that in use the induced quadrature signal is substantially rejected by the amplifier in the absence of a fault condition, and the amplifier outputs an induced quadrature signal when a fault condition disconnects one of the skew transducers from the amplifier, and a comparator compares the quadrature output from the pickoff amplifier with a predetermined threshold value and provides a fault indication when the predetermined threshold is exceeded.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

An accelerometer comprises a support (12), a proof mass (14) supported for movement relative to the support (12) by a plurality of mounting legs (16), a plurality of fixed capacitor fingers associated with the support (12) and a plurality of movable capacitor fingers associated with the proof mass (14), the fixed capacitor fingers being interdigitated with the movable capacitor fingers, the mounting legs (16) being of serpentine shape, each mounting leg (16) comprising at least a first generally straight section (16a), a second generally straight section (16a), and an end section (16b) of generally U-shaped form interconnecting the first and second generally straight sections (16a), wherein the thickness Te of the end section (16b) is greater than the thickness Tc of a central part (16c) of both of the first and second generally straight sections (16a).

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up

Abstract

An accelerometer comprises a support, a first mass element and a second mass element, the mass elements being rigidly interconnected to form a unitary movable proof mass, the support being located at least in part between the first and second mass elements, a plurality of mounting legs securing the mass elements to the support member, at least two groups of movable capacitor fingers provided on the first mass element and interdigitated with corresponding groups of fixed capacitor fingers associated with the support, and at least two groups of movable capacitor fingers provided on the second mass element and interdigitated with corresponding groups of fixed capacitor fingers associated with the support.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/18 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration in two or more dimensions

Abstract

A silicon MEMS gyroscope is described having a ring or hoop-shaped resonator (1). The resonator (1) is formed by a Deep Reactive Ion Etch technique and is formed with slots (5) extending around the circumference of the resonator (1) on either side of the neutral axis (4) of the resonator (1). The slots (5) improve the Quality Factor Q of the gyroscope without affecting the resonant frequency of the resonator.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Goods & Services

Measuring apparatus and instruments; navigational apparatus and instruments; inertial measurement units; angular rate sensors; gyroscopes; global positioning apparatus and instruments; parts and fittings for all the aforesaid goods.

Goods & Services

Measuring apparatus and instruments; navigational apparatus and instruments; inertial measurement units; angular rate sensors; gyroscopes; global positioning apparatus and instruments; parts and fittings for all the aforesaid goods.

Abstract

An exemplary vibrating structure gyroscope includes a ring structure, an external frame and a flexible support including a pair of symmetrical compliant legs arranged to retain the ring structure within the external frame. A metal track is provided on an upper surface of the ring structure, the compliant legs and the external frame, over an insulating surface oxide layer. Each flexible support is arranged to carry a metal track associated with a single drive or pick-off transducer. The metal track is repeated for eight circuits, one circuit for each transducer. Each circuit of metal track associated with a transducer begins at a first bond-pad on the external frame, runs along a first compliant leg, across an eighth segment of the ring structure and back along the other compliant leg to a second bond-pad on the external frame.

IPC Classes  ?

• G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces

Abstract

An accelerometer open loop control system comprising a variable capacitance accelerometer having a proof mass movable between fixed capacitor plates, drive signals applied to the capacitor plates, a charge amplifier amplifying an accelerometer output signal representing applied acceleration, and an autoranging facility for monitoring the output signal, and for adjusting the drive signals in dependence on the output signal in order to restrict the amplitude of the accelerometer output signal, thus maintaining sensitivity of the accelerometer while permitting response to a wide range of g values. Corrections are applied by means of look up tables to compensate for inaccuracies arising from movement of the proof mass and temperature variations.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up

Abstract

p is arranged to generate a predetermined electrostatic force, which acts upon the ring structure 42 to locally adjust the stiffness of the ring structure 42. p reduces the effect of variation a capacitive gap with ring structure 42 due to temperature change, thereby improving the scalefactor of the gyroscope structure.

IPC Classes  ?

• G01P 9/04 - using turn-sensitive devices with vibrating masses, e.g. tuning-fork

Abstract

An angular velocity sensor or gyroscope has a ring and a primary drive transducer arranged to cause the ring to oscillate in a primary mode substantially at the resonant frequency of the primary mode of the ring. A primary control loop receives primary pick-off signals from the primary pick-off transducer and provides primary drive signals to the primary drive transducer so as to maintain resonant oscillation of the ring. The primary control loop includes a demodulator arranged to determine the amplitude of the fundamental frequency of the primary pick-off signals and a demodulator arranged to determine the amplitude of the second harmonic frequency of the primary pick-off signals and a drive signal generator arranged to produce the primary drive signals with an amplitude that is dependent on a ratio of the amplitude of the second harmonic frequency of the primary pick-off signal over the amplitude of the fundamental frequency of the primary pick-off signal as derived by a divider.

IPC Classes  ?

• G01C 19/56 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces

Abstract

A vibrating structure gyroscope includes a ring structure (52), an external frame (58) and a flexible support (56e) including a pair of symmetrical compliant legs (60a, 60b) arranged to retain the ring structure (52) within the external frame (58). Metal track (80) is provided on an upper surface of the ring structure (52), the compliant legs (60a, 60b) and the external frame (58), over an insulating surface oxide layer, not illustrated. Each flexible support (56e) is arranged to carry metal track (80) associated with a single drive or pick- off transducer. The metal track (80) is repeated for eight circuits, one circuit for each transducer. Each circuit of metal track (80) associated with a transducer begins at a first bond-pad (82) on the external frame (58), runs along a first compliant leg (60a), across an eighth segment (84) of the ring structure (52) and back along the other compliant leg (60b) to a second bond-pad 86 on the external frame (58).

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A gyroscope has a ring (70) and a primary drive transducer (72) for oscillating the ring (70) substantially at the resonant frequency in a primary mode. A primary control loop receives primary pick-off signals from the primary pick-off transducer (74) and provides primary drive signals 116 to the primary drive transducer (72) so as to maintain resonant oscillation of the ring (70). The primary control loop includes a demodulator (78) determining the amplitude of the fundamental frequency of the primary pick-off signals and a demodulator (82) determining the amplitude of the second harmonic frequency of the primary pick-off signals and a drive signal generator (100, 106, 110 and 114) producing the primary drive signals (116) with an amplitude that is dependent on a ratio of the amplitude of the second harmonic frequency of the primary pick-off signal over the amplitude of the fundamental frequency of the primary pick-off signal as derived by a divider (100).

IPC Classes  ?

• G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators